Robotic threads aim to run through the brain's blood vessels | MIT News

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MIT engineers have developed a magnetically steerable wire-like robot that can actively glide through narrow, winding paths, such as the brain’s labyrinthine vasculature.
In the future, this robotic thread may be combined with existing endovascular technology, allowing doctors to remotely guide a robot through a patient’s brain blood vessels to rapidly treat blockages and lesions, such as those that occur in aneurysms and strokes.
“Stroke is the fifth leading cause of death and the leading cause of disability in the United States. If acute strokes can be treated in the first 90 minutes or so, patient survival may be significantly improved,” says MIT Mechanical Engineering and Zhao Xuanhe, associate professor of civil and environmental engineering, said.”If we can design a device to reverse vascular blockage during this ‘prime time’ period, we could potentially avoid permanent brain damage. That’s our hope.”
Zhao and his team, including lead author Yoonho Kim, a graduate student in MIT’s Department of Mechanical Engineering, describe their soft robot design today in the journal Science Robotics.Other co-authors of the paper are MIT graduate student German Alberto Parada and visiting student Shengduo Liu.
To remove blood clots from the brain, doctors usually perform endovascular surgery, a minimally invasive procedure in which the surgeon inserts a thin thread through a patient’s main artery, usually in the leg or groin.Under fluoroscopic guidance, which uses X-rays to simultaneously image the blood vessels, the surgeon then manually rotates the wire up into the damaged brain blood vessels.The catheter can then be passed along the wire to deliver the drug or clot retrieval device to the affected area.
The procedure can be physically demanding, Kim said, and requires surgeons to be specially trained to withstand the repeated radiation exposure of fluoroscopy.
“It’s a very demanding skill, and there simply aren’t enough surgeons to serve patients, especially in suburban or rural areas,” Kim said.
Medical guidewires used in such procedures are passive, meaning they must be manipulated manually, and are often made of a metal alloy core and coated with a polymer, which Kim says can create friction and damage the lining of blood vessels.Temporarily stuck in a particularly tight space.
The team realized that developments in their lab could help improve such endovascular procedures, both in the design of guidewires and in reducing physicians’ exposure to any associated radiation.
Over the past few years, the team has built up expertise in hydrogels (biocompatible materials mostly made of water) and 3D printing magneto-actuated materials that can be designed to crawl, jump and even catch a ball , just by following the direction of the magnet.
In the new paper, the researchers combined their work on hydrogels and magnetic actuation to produce a magnetically steerable, hydrogel-coated robotic wire, or guidewire, that they were able to Made thin enough to magnetically guide blood vessels through life-size silicone replica brains.
The core of the robotic wire is made of nickel-titanium alloy, or “nitinol,” a material that is both bendable and elastic.Unlike hangers, which retain their shape when bent, the nitinol wire returns to its original shape, giving it more flexibility when wrapping tight, tortuous blood vessels.The team coated the core of the wire in rubber paste, or ink, and embedded magnetic particles in it.
Finally, they used a chemical process they had previously developed to coat and bond the magnetic overlay with a hydrogel—a material that does not affect the responsiveness of the underlying magnetic particles, while still providing a smooth, Friction-free, biocompatible surface.
They demonstrated the precision and activation of robotic wire by using a large magnet (much like a puppet’s rope) to guide the wire through the obstacle course of a small loop, reminiscent of a wire passing through the eye of a needle.
The researchers also tested the wire in a life-size silicone replica of the brain’s major blood vessels, including clots and aneurysms, that mimicked CT scans of an actual patient’s brain.The team filled a silicone container with a liquid that mimics the viscosity of blood, then manually manipulated large magnets around the model to guide the robot through the container’s winding, narrow path.
Robotic threads can be functionalized, Kim says, meaning that functionality can be added—for example, delivering drugs that reduce blood clots or breaking blockages with lasers.To demonstrate the latter, the team replaced the threads’ nitinol cores with optical fibers and found that they could magnetically guide the robot and activate the laser once it reached the target area.
When the researchers compared the hydrogel-coated robotic wire with the uncoated robotic wire, they found that the hydrogel provided the wire with a much-needed slippery advantage, allowing it to glide through tighter spaces without won’t get stuck.In endovascular procedures, this property will be key to preventing friction and damage to the lining of the vessel as the thread is passed.
“One challenge in surgery is being able to traverse the complex blood vessels in the brain that are so small in diameter that commercial catheters cannot reach,” said Kyujin Cho, a professor of mechanical engineering at Seoul National University. “This study shows how to overcome this challenge. potential and enable surgical procedures in the brain without open surgery.”
How does this new robotic thread protect surgeons from radiation?The magnetically steerable guidewire eliminates the need for surgeons to push the wire into a patient’s blood vessel, Kim said.This means that the doctor also doesn’t have to be close to the patient and, more importantly, the fluoroscope that produces the radiation.
In the near future, he envisions endovascular surgery incorporating existing magnetic technology, such as pairs of large magnets, allowing doctors to be outside the operating room, away from fluoroscopes that image patients’ brains, or even in completely different locations.
“Existing platforms can apply a magnetic field to a patient and perform a fluoroscopy at the same time, and the doctor can control the magnetic field with a joystick in another room, or even in a different city,” Kim said.”We hope to use existing technology in the next step to test our robotic thread in vivo.”
Funding for the research came in part from the Office of Naval Research, MIT’s Soldier Nanotechnology Institute, and the National Science Foundation (NSF).
Motherboard reporter Becky Ferreira writes that MIT researchers have developed a robotic thread that could be used to treat neurological blood clots or strokes.Robots could be equipped with drugs or lasers that “could be delivered to problem areas of the brain. This type of minimally invasive technology may also help mitigate damage from neurological emergencies such as strokes.”
MIT researchers have created a new thread of magnetron robotics that can meander through the human brain, Smithsonian reporter Jason Daley writes.”In the future, it could travel through blood vessels in the brain to help clear blockages,” explains Daly.
TechCrunch reporter Darrell Etherington writes that MI researchers have developed a new robotic thread that could be used to make brain surgery less invasive.Etherington explained that the new robotic thread could “may make it easier and more accessible to treat cerebrovascular problems, such as blockages and lesions that can lead to aneurysms and strokes.”
MIT researchers have developed a new magnetically controlled robotic worm that could one day help make brain surgery less invasive, reports New Scientist’s Chris Stocker-Walker.When tested on a silicon model of the human brain, “the robot can wriggle through hard-to-reach blood vessels.”
Gizmodo reporter Andrew Liszewski writes that a new thread-like robotic work developed by MIT researchers could be used to quickly clear blockages and clots that cause strokes.”Robots could not only make post-stroke surgery faster and faster, but also reduce the radiation exposure that surgeons often have to endure,” Liszewski explained.

Post time: Feb-09-2022